The present invention generally relates to capsules for containing beverage ingredients, to a beverage producing system comprising such capsules as well as to methods for producing beverages on the basis of ingredients contained in such capsules.
Note that the term “beverage” is meant to also encompass liquid comestibles in the framework of the present specification and the enclosed claims.
The background of the present invention is the field of capsules which contain beverage ingredients or other comestible (e.g. soup) ingredients. By means of an interaction of these ingredients with a liquid, a beverage or other comestibles, such as for example soups, can be produced. The interaction can be for example an extraction, brewing, dissolution, mixing etc. process. Such a capsule is e.g. adapted to contain ground coffee in order to produce a coffee beverage by having hot water under pressure enter the capsule and draining a coffee beverage from the capsule.
Systems and methods for obtaining liquid comestibles from capsules are for example known from EP-A-512470 (counterpart of U.S. Pat. No. 5,402,707), the teaching of which will be explained in the following.
The capsule 101 as shown in FIG. 1 has a frustoconically-shaped cup 102 which may be filled e.g. with roasted and ground coffee 103 and which is closed by a foil-like tear face cover 104 welded and/or crimped to a flange-like rim which extends laterally from the side-wall of cup 102. A capsule holder 111 comprises a flow grill 112 with relief surface element members 113.
The capsule holder 111 is accommodated in its support 115 which has a lateral wall 124 and a bore 127 for the passage of extracted coffee beverage.
As can be seen from FIG. 1 the extraction system further comprises a water injector 107 having a water inlet channel 120 and an annular element 108 with an internal recess of which the shape substantially corresponds to the outer shape of the capsule. On its outer part, the annular member 108 comprises a spring 122 holding a ring 123 for releasing the capsule on completion of extraction.
In operation, a capsule 101 is placed in the capsule holder 111. The water injector 107 perforates the upper face of the cup 102. The lower tear face 104 of the capsule rests on the radially arranged members 113 of the capsule holder 111.
The water is injected through the channel 120 of the water injector 107 and impinges on the bed 103 of coffee. The pressure in the capsule 101 increases and the tear face 104 increasingly follows the shape of the radial opening relief members 113. Such radial opening relief members could be replaced by pyramid-shaped reliefs or other shapes of relief. When the constituent material of the tear face reaches its breaking stress, the tear face tears along the relief members. The extracted coffee flows through the orifices of the flow grill 112 and is recovered in a container (not shown) beneath the bore 127.
The principles of this extraction process as far as they can be maintained in connection with the present invention can be summarized as follows:                An initially sealed capsule is inserted into a capsule enclosure space of the machine;        The capsule enclosure space is closed by transferring enclosing members from an opened state into a capsule-enclosing state.        In a first wall of the capsule at least one opening is generated and a liquid under pressure is injected into the capsule.        The pressure inside the capsule assists in the opening of an outlet face of the capsule.        Water entering the capsule through the opening in the first wall is interacting with the ingredients contained in the capsule while traversing the interior of the capsule and is then made to leave the capsule through the opened outlet face.        
The ingredients in the capsule preferably constitute the “bottleneck” of the flow path of the water and will therefore cause a pressure drop between the upstream and the downstream side of the liquid flow through the capsule, which pressure drop can even increase during the interaction between the liquid and the ingredients for example due to a swelling of the ingredients. Correspondingly it has to be assured that the only water flow is actually taking place through the interior of the capsule (arrow A1) and that no water can flow from the water injector into the interstice between the annular enclosing member 108 and the exterior of the capsule 101 and then to the draining bore 127 of the device. The arrow A2 illustrates this undesired water flow path.
In other words, any water flow exterior to the capsule 101 has to encounter a substantial flow obstacle produced by a sealing engagement being positioned in the interstice between the annular member 108 and the capsule 101 and in the flow path between the water injector and the beverage outlet.
In case the sealing engagement is not working at all and water is flowing outside the capsule without encountering a sufficient flow resistance, the pressure necessary to cause the tearing of the outlet face will not be built up inside the capsule or, alternatively, the low pressure will result in an incomplete tearing of the outlet face and therefore a poor extraction of the substance. In such a scenario water will be drained from the beverage production device without having interacted or fully interacted with the ingredients contained in the capsule under sufficient pressure conditions.
An improvement could be thought of according to which the sealing engagement is assisted by lining the inner wall of the annular member with a rubber-elastic material. According to said approach the sealing engagement is assured by structures fixed to or attached with the beverage-producing device. This has disadvantages in that after the use of a substantial number of capsules a wearing off of the fixed sealing means can take place such that the quality of the produced beverage is increasingly deteriorated by water passing the no longer properly efficient sealing.